Systematics

• The study of the diversity of organisms.  Includes:
• ____________
• Naming of organisms
• ____________
• Placing organisms into a group based on their relationships and similarities
• Carolus Linnaeus
• Father of modern classification
• Developed _____________  ______________
  
• Each organism on Earth recognized by a unique two-part name:
• Genus + specific epithet = species
• e.g. Odocoileus virginianus
• White-tailed deer
• Odocoileus hemionus
• Mule deer
• Names are usually descriptive or related to a person or place;
• Escherichia coli
• Named for Theodor Escherich who first described this bacteria
• coli because it lives in our colon

Taxonomic Hierarchy of Classification

• SPECIES are the basic units - only units that are real from a biological standpoint.
• Closely related species put into a GENUS (genera pl.)
• Closely related genera put into a FAMILY
• Closely related families put into an ORDER
• Closely related order placed into a CLASS
• Related classes placed into a PHYLUM (phyla pl.)
• Phyla are placed into KINGDOMS
• Kingdoms are placed into DOMAINS

Human Classification

Classification

• Groups organisms together because they share a common ancestor.
• Goal is to place organisms in monophyletic groups
• The practice of grouping organisms together this way is called ____________.
• Cladistics groups organisms together based on ________________ characters
• Shared, derived (or new) characters
• Cladograms are used to place organisms into our taxonomic system.

Diversity of Life on Earth

• Diversity refers to the number of different kinds of organisms that are present.
• When we refer to diversity, it usually means the number of species.
• What is a species?

Biological Species Concept

• Groups of reproducing organisms that are reproductively isolated from other similar groups of organisms.
• Barriers to reproduction can occur either prior to trying to breed:
• Prezygotic barriers
• Or after mating has already taken place
• Postzygotic barriers

What processes have led to the species diversity that we see today?

• Two general models to describe species formation = speciation:
• 1 ) _______________ speciation
• new species arise when the parent species becomes separated into two or more populations
• Speciation occurs due to the natural change in organisms over time.
• New species arise only if they are unable to interbreed when (if) the populations are reunited.
• 2) ________________speciation
• new species arise from within the geographic range of the original species.
• Either type of speciation can, over time, result in an increase in diversity
• Cladogenesis
• Other changes may lead to speciation without increasing diversity
• Anagenesis